U.S. Pat. No. 3,996,064 to Thaller discloses a rechargeable REDOX flow cell utilizing anode and cathode fluids. The cell utilizes a semi-permeable anion membrane and primarily discusses the iron-chromium couple although other metal ions species are indicated as being useful.
U.S. Pat. No. 4,159,366 to Thaller discloses an iron-hydrogen electrochemical rebalance cell for maintaining electrochemical balance between the reactants of an iron-chromium REDOX system.
U.S. Pat. No. 4,370,392 to Savinell and Liu discloses a chromium-chlorine REDOX energy storage system. This is a rechargeable storage device in which iron could not be used as an anode material since chlorine and iron are both cathode materials.
U.S. Pat. No. 3,540,933 to Boeke describes a liquid reactant fuel cell in which the reactants are separated by a porous membrane between the anode and cathode compartments. The reactants are acidic solutions containing a combination of at least two metal ion complexes. Reactants are chemically charged by reducing one-half of the solution with methanol and oxidizing the other half with hydrogen peroxide or air. The charged reactants are then electrochemically discharged in the fuel cell.